Cam assemblies are well known for converting one pattern of motion to another. In a typical example, a cam is moved relative to a frame or scaffold by a motivating input force such as a motor, and a cam surface is configured to move a follower (which is movably supported by the frame in a position so as to engage the cam surface) that tracks along the cam surface. The contour of the cam surface (which may be a surface, slot, or other structure designed to guide the motion of the follower engaged therewith) displaces the follower such that the follower produces the desired output pattern of movement. For example, a cam having an eccentric cam surface may rotate to convert rotary motion to linear motion of a follower that is displaced by the eccentric surface as the cam rotates. In many cases, a cam is employed to convert simple motion, such as constant-speed rotation or reciprocating movement, to a desired output waveform, such as a sinusoidal or trapezoidal displacement of the follower, potentially with dwell periods where the position of the follower does not change.
Various cam types are well known in the art, including rotating cams having a peripheral cam surface with a radius that varies around the circumference, rotating cylindrical cams having a cam surface with a constant radius but which varies in position in a direction orthogonal to the axis of rotation, reciprocating cams which translate back and forth along an axis, stationary cams where the cam surface remains fixed to the frame and the follower is moved relative to the cam, etc. Variations on the basic cam designs also exist. For example, most cams can be made as a conjugal cam where the follower contact portion has opposed contact points that follow opposed portions of the cam surface(s).
There are many ways to synthesize cam and follower profiles based on desired output waveforms, and such algorithms are well-known. For example, given different positions that the cam follower should assume at different times, the curves between positions on the cam surface can be determined assuming a constant velocity or constant acceleration, or the curves may be cubic, cycloidal, harmonic, trapezoidal, sinusoidal, 345-polynomial, 4567-polynomial, or any of many others. Commercial software is available to create cam profiles, for example, Analytix Cams (Saltire Software, Oregon, US) is specifically for cam design, and more general programs such as Autodesk Inventor and AutoCAD (Autodesk, California, US), have cam design and simulation features.
Issues like jerk and chatter are largely dependent on the operating speed of the cam, and one purpose of some cam profile generation algorithms is to minimize these phenomena. However, jerk and chatter aside, and even at low speeds, the accuracy of the resulting output waveform is typically dependent on the smoothness of the cam surface, since unintended variations in the cam surface may translate to noise or other unintended variations in the cam follower position. This problem is typically avoided with precise machining and other steps (e.g., polishing), which gives the cam a smooth surface, but which also increase the expense and effort of fabrication.